On Wednesday, 133 cardinals will gather in the Sistine Chapel to select the next pope.

It is called the conclave and it is one of the oldest election processes in the world. For days – perhaps even weeks – the cardinals in Rome will vote again and again until one candidate wins a two-thirds majority. Then, and only then, will they be named as the successor to Pope Francis.

It is, as Guardian journalist Harriet Sherwood explains, an election rich in ceremony and ritual. Yet it can get very dirty too: cardinals lobbying in corridors and Vatican gardens; allegations of leaks to the media to discredit rivals; even the emergence of a video of one cardinal – a bookies’ favourite to be the next pope – singing ‘atheist anthem’ Imagine by John Lennon.

As Michael Safi hears, the conclave comes at a particularly sensitive time for the Catholic church and the various factions vying for its control.

So who will be named pope when the famous white smoke emerges?